This invention relates to a tone generation device having a tone generation delay function (hereinafter referred to as "key-on delay") and, further, to an electronic musical instrument capable of obtaining, by utilizing the key-on delay, an ensemble effect according to which tones of an ensemble performance can be produced.
In a prior art tone generation device, the key-on delay has been used as a method for obtaining an ensemble effect. According to the key-on delay processing, tones of the same tone pitch and tone color are generated individually in two tone generation lines with one tone being generated with a delay from generation of the other tone and, therefore, phases of tone waveforms of the tones generated in the two lines are caused to vary and the ensemble effect is thereby obtained (e.g., Japanese Laid-open Patent Publication Hei2-181795).
In the prior art tone generation device, however, time length during which it is desired to delay the timing of start of tone generation (i.e., delay time) is counted by a counter and this necessitates provision of counters for all tone generation channels with resulting complexity of the circuit design.
Besides, in such key-on delay processing, if the delay time is constant, the phase relation between the two tone generation lines will vary for each tone pitch and, in some case, phases of the two lines will differ by 180 degrees depending upon the tone pitch. In this case, the tones generated in the two lines will cancel each other depending upon the waveform of the tones. For avoiding this cancellation of the tones, it is necessary to differ the delay time in accordance with the tone pitch but this will require a further complicated circuit design.